In general, an electric current, such as a pulsed current or a high alternate current, is measured in a manner that a measurement-target current is applied to flow through a shunt resistor having a known resistance value, and a voltage drop occurring in the shunt resistor is measured. The applicant already proposed a shunt resistor of the aforementioned type, as shown in FIG. 11 (refer to Japanese Unexamined Patent Application Publication No. 2000-131349). The conventional shunt resistor disclosed in the publication is configured such that two substantially planar resistors 6a and 6b are connected together at their one-side edges substantially to form the letter “U”. One-side ends of substantially L-shaped fixed plates 2a and 2b are connected to the other-side edges of the respective resistors 6a and 6b. In addition, a pair of lead wires 40 and 40 are individually connected by spot welding or a like manner to the vicinities of connection portions to the fixed terminal plate; 2a and 2b fixed to the individual resistors 6a and 6b, in which the lead wires 40 and 40 individually take a voltage drop, which occurs with the resistors 6a and 6b, in the form of a voltage signal when a measurement-target current is applied to the shunt resistor through the fixed terminal plates 2a and 2b. 
According to above-described the conventional example, however, the lead wires 40 and 40 are connected to surfaces of the individual resistors 6a and 6b, and hence the lead wires 40 and 40 are extended in the directions of sidewalls of the resistors 6a and 6b facing the fixed terminal plates 2a and 2b. As such, the configuration is restricted in that portions in the directions of the sidewalls of the resistors 6a and 6b must be kept open, therefore arising the problem of reducing the degree of freedom in design. For example, in case of providing the fixed terminal plates 2a and 2b on a heat-dissipating plate, lead wires 40 and 40 extended in the direction of the sidewalls of resistors 6a and 6b become hindrances, there occurs a problem that a shape of the heat-dissipating plate is complicated or it is grown in size in order to avoid lead wires 40 and 40.
The present invention is made in view of the above-described problems. Accordingly, an object of the invention is to provide a shunt resistor that eliminates the structural restriction and enables the degree of freedom in design to be enhanced.
Another object of the present invention is to provide a resistance-value adjusting method for the shunt resistor to enable the resistance value of a resistor to easily be adjusted.